The energy spectrum of cosmic rays above 2.5 x 10^18 eV, derived from 20 000 events recorded at the Pierre Auger Observatory, is described. The spectral index \gamma of the particle flux, J proportional to E^(-gamma), at energies between 4 x 10^18 eV and 4 x 10^19 eV is 2.69 +- 0.02(stat) +- 0.06(syst), steepening to 4.2 +- 0.4(stat) +- 0.06(syst) at higher energies. The hypothesis of a single power law is rejected with a significance greater than 6 standard deviations. The data are consistent with the prediction by Greisen and by Zatsepin and Kuz’min.

Observation of the suppression of the flux of cosmic rays above 4 x 10^19 eV

BERNARDINI, Paolo;DE MITRI, Ivan;MANCARELLA, Giovanni;MARTELLO, Daniele;PERRONE, Lorenzo;
2008

Abstract

The energy spectrum of cosmic rays above 2.5 x 10^18 eV, derived from 20 000 events recorded at the Pierre Auger Observatory, is described. The spectral index \gamma of the particle flux, J proportional to E^(-gamma), at energies between 4 x 10^18 eV and 4 x 10^19 eV is 2.69 +- 0.02(stat) +- 0.06(syst), steepening to 4.2 +- 0.4(stat) +- 0.06(syst) at higher energies. The hypothesis of a single power law is rejected with a significance greater than 6 standard deviations. The data are consistent with the prediction by Greisen and by Zatsepin and Kuz’min.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11587/106234
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